Chemical Hazards In The Working Environment Environmental Sciences Essay

Chemical Hazards In The Working Environment Environmental Sciences Essay Chemical Engineering is defined as the branch of engineering which is involved in the application of physical science and mathematics to processing and converting raw materials and chemicals into more useful forms. The outputs and methods of these processes are not always safe and chemical hazards need to be overcome to make the working environment a satisfactorily hospitable for everyone that the process affects. This includes the general public and the environment as well as the workers involved. Chemical Engineers need to ensure that the safety measures which they devise regarding certain processes are adequate enough not to pose hazards and to meet the regulations of the law. This term paper will outline some of the hazards which Chemical Engineers and other workers in the industry need to neutralise to ensure that the working environment is safe for those involved. A hazard is defined as anything which could result in an accident. Such hazards include those caused by the release of noxious chemicals which can prove damaging to the health of people and the environment. Chemical hazards can be especially dangerous due to the toxic nature of the substances used in the industry. Plant Safety The health and safety of plant workers is a major concern to the chemical industry. Accidents which result in loss of life or injuries are especially damaging due to the high costs they inflict. Costs in retraining personnel, repairing equipment damaged in have huge costs, as well as the interruption in business that ensues after an accident. The trends have shown that over the years fatalities have decreased but property costs have increased. This trend is due to the increased automated systems used in plants. These systems have increased complexity and productivity to older designs. In earlier designs the workers were more exposed to the chemical processes taking place in the plant, and were in turn exposed to more hazards. This however poses another problem because if workers are more isolated from a process, even if this greatly reduces health and safety hazards then if a malfunction occurs in the plant it is much more difficult to have experienced personnel available to fix a process problem. Due to this action compensation must be made in the case of higher property costs as opposed to loss of life and injury to workers. As of the early 1990s, annual worker fatalities ran about 9 per 100,000 employees; annual lost time disabling injuries ran about 4,000 per 100,000 employees. Property Losses increased fourfold from the 1970s. Safety assessments are now undergone on chemical plants to ensure that they adhere to safety levels proposed by regulation standards. Quantification of hazards such as overpressure potential and flammability were done by measurements of vapour pressure and of flash points and flammability limits. The process designers need to make use of data that gives information pertaining to the hazards of a process such as information of reaction rates and the energies involved in exothermic reactions in which heat is given out, that of unstable chemicals, of temperature limits in which explosive decomposition can occur, rates of generation of gas and vapour and emergency fail-safes such as pressure releases for high pressure systems. Citing Wikipedia, Fault tree analysis (FTA) is a failure analysis in which an undesired state of a system is analyzed using Boolean logic to combine a series of lower-level events. This is used to quantitatively combine the characteristics of human and component failure rates to obtain a safety assessment for that process. Many changes arose in the 1980s and 1990s regarding safety requirements in the petrochemical and chemical industry. These were presented by industrial groups such as Chemical Manufacturers Association as and the American Petroleum Institute as consensus guidelines. The objective of these changes was to make sure that all members of these industries were designed, maintained and controlled in the safest way that would be economically viable. Kirk Othmer (1991-1998). Hazard Analysis and Risk Assessment Hazards associated with in facilities can be in the order of hundreds or thousands if the facility is large enough. These hazards occur as a result of factors such as the type of physical materials being used, the processes that are designed to make a product, the operating conditions and the design of a plant to name but a few. If hazards arent controlled a sequence of events can occur which will result in an accident. A hazard can result in an accident which is an unplanned sequence of events which can result in the loss of life, damage to the environment, damage to products and inventory and damage to equipment. Risk involves probability and consequence of something undesirable occurring. It is impossible to completely define a risk without taking both of these components into consideration. For example a hazard could involve a large consequence but also could have a very low probability of causing an accident or vice versa. In both these cases it would be classed as a moderate risk. The purpose of hazard analysis and risk assessment is therefore to characterise hazards, determine the probability of them occurring and then to consider and evaluate the consequences if an accident did occur. This procedure can be summed up by this flow chart in Figure 1. Flow chart describing the full hazard analysis and risk assessment procedure Fig. 1 Kirk Othmer (1991-1998) Flow Chart Explanation A committee is required to perform hazard analysis and risk assessment. Each member of the committee must have adequate experience to the chemical process that is being considered. The first step is to consider a detailed account of the process which describes it completely. This has to include the physical properties of the materials being used, instrument diagrams of processes, operating temperatures and pressures, materials for the construction of the equipment being used and any other detailed design specifications. The more detailed and updated this is, the more effective the analysis will be. The next step involves identifying the hazards involved in the process. This is done by a certain number of established procedures. In this step it is not uncommon to find hundreds of hazards for complex processes. The next step involves identifying all the scenarios which could result in the loss of control of the system, therefore resulting in an accident. This can be seen to be the most difficult step in the analysis. Most accidents occur due to improper accident scenario characterisation. Many complex chemical processes can have hundreds of different accident scenarios for each hazard but the most important part of this analysis is to pick the scenarios which are most dire but at the same time credible. Risk assessment is the next part of the procedure. This involves determining accident probability and the consequences involved. This procedure is performed for all the accident scenarios that were identified in the last step. Statistical models used to represent failures are the method preferred for determining the probability of each accident. Source models are used to provide information about how material would be ejected from equipment, along with dispersion and explosion models, a good estimate can be made to the cost of the damage to the affected areas. Thus the consequence is now determined. The final part of this procedure is to decide whether the risks involved are acceptable. If they are not then changes must be made and the process must be restarted to ensure that they are subsequently neutralised. If the risk is an acceptable one then the process can go ahead and be implemented. Hazard analysis or risk assessment can be undergone at any time during the course of a process life. It is however, must more cost effective to perform this procedure at the initial stages where changes would be less costly to implement. Process Safety Management Several incidents which occurred in the late twentieth century indicated that there needed a significant improvement in the management of process hazards. There are three incidents that have produced the greatest legislative response. These incidents are as follows The Flixborough disaster, U.K. 1st June 1974 in which a temporary bypass pipe ruptured causing 40 tonnes of cyclohexane to form a vapour cloud 100-200 metres in diameter. The cloud came in contact with an ignition source and exploded causing 1,800 buildings within a mile radius of the site were damaged. 28 dead. 89 serious injuries. Wikipedia, Flixborough Disaster (2010) The Bhopal disaster, India. 3rd December 1984 in which a runaway reaction caused by water entering tank 610 containing 42 tonnes of methyl isocyanate vented to the surrounding areas forming a toxic cloud. ca. 3,000 dead. ca. 200,000 serious injuries. Wikipedia, Bhopal Disaster (2010) Polyethylene Plant Explosion, Pasadena, Texas. 23rd October 1989 in which a valve failure caused a large amount of flammable gas to be released which subsequently exploded. 23 dead. 130-300 serious injury. (www.cholarisk.com//Philips%20PE%20Pasadona%20Explosion.ppt). Standards and guidelines have been developed to ensure that these types of accidents do not occur again by improving management of process safety. The Health and Safety at Work Act developed by the Health and Safety Executive (HSE) was devised following the Flixborough disaster this meant that the HSE would require that the type or quantity of chemical used or produced was to be registered and also the HSE submitted recommendations for maintenance functions plant design and methods for evaluating process hazards. The Occupational Safety and Health Act devised by the Occupational Safety and Health Administration (OSHA) which was enacted in 1970 established standards for occupational hazards such as toxicity, equipment guarding and protection against falling, noise and electrical shock. The New Jersey Toxic Catastrophe Prevention Act was developed after the Bhopal disaster and several other incidents such as that of Institute, West Virginia in 1985 and several chemical release incidents in New Jersey in 1986. This required for each of the 109 materials listed in regulations to be registered based on attainment of a material that can cause acute toxicity at a distance of 100m from a source of 1 hour release. Kirk Othmer (1991-1998). Safety and Hazard symbols A hazard symbol is defined as a recognised symbol that is designed to warn about dangerous locations or materials. NFPA 704- National Fire Protection Association NFPA 704 or the fire diamond is a standard maintained by the National Fire Protection Agency in the US. This standard is used by emergency personnel to easily and quickly identify the types of nearby hazards and to help determine what sort of equipment, precautions or procedures would need to be adhered to following an emergency response. There are symbols attached to the fire diamond which each signify a particular type of hazard. They are colour coded. Red signifies a flammability hazard, blue signifies a health hazard, yellow signifies an instability or reactivity hazard and white signifies a specific hazard such as a material that reacts unusually with water such as sodium or certain alkali metals, a specific hazard can be anything from a biological hazard to a corrosive hazard. Each of these hazards is ranked according to the level of risk they pose to personnel. It is ranked with 5 gradations, 4 being the highest and 0 being the lowest; this would pose no hazard at all. For each of the different types of hazards this high level of risk has a different definition. For a flammability hazard of 4 this would mean that the material has a flash point below that of room temperature and will burn readily at regular pressures and temperatures. Propane is an example of such a hazardous substance. For a health hazard of 4 this would signify that if one were exposed to the material for a short amount of time that it could cause death. An example of this would be hydrogen cyanide or phosphine. For an instability or reactivity hazard of 4 this would signify a substance that would be readily capable of detonation or decomposition at normal temperatures and pressure, such an example of this would be nitroglycerine. On the other end of the scale, a flammability hazard of 0 would be a substance that would not burn under any conditions such as water. A health hazard of 0 would be a substance that would pose no health hazard at all such as that of lanolin ointment. An instability/reactivity hazard of 0 would be a substance that is normally stable, even if it is exposed to fire, such as helium or any inert gas. These are some examples of the fire diamonds for various substances nfpa_diamond.png fire diamond for ethanol.jpg caffeine fire diamond.jpg Fig 2.1 Nitroglycerine Fig 2.2 Ethanol Fig 2.3. Caffeine Another method by which hazards can be averted is by specifying the types of precautions needed in handling potentially dangerous chemicals. The Hazardous Materials Identification Guide (HMIG) and Hazardous Materials Information System (HMIS) use a different system which signifies what type of protective equipment is needed when handling a certain chemical. This method is similar to the NFPA 704 (fire diamond). The differences lie in the white bar. In this system the white bar holds letters corresponding to different types of Personal Protective Equipment (PPE) which are needed. The letters used are A-K and X and mean the same for both the HMIG and HMIS. They are also augmented with pictures of what icons are pictures showing the types of PPE that would be needed. HMIG.gif Fig 2.4 (HMIG) Safety Glasses Safety Glasses, Gloves Safety Glasses, Gloves, Apron Face Shield, Gloves, Apron Safety Glasses, Gloves, Dust Respirator Safety Glasses, Gloves, Apron, Dust Respirator Safety Glasses, Gloves, Vapour Respirator Splash Goggles, Gloves, Apron Vapour Respirator Safety Glasses, Gloves, Dust and Vapour Respirator Splash Goggles, Gloves, Apron, Dust and Vapour Respirator Air Line Hood or Mask, Gloves, Full suit, Boots X- Ask Supervisor or Safety Specialist for handling instructions Hazardous Materials Regulations In an operation where chemicals are manufactured and distributed the role of packaging these chemicals safely is an important priority to the chemical industry. Careful consideration must be made to ensure that the packaging used provides adequate containment of any hazards that may be held in the packaging so as to ensure that it can be transported safely from the place of manufacture to where it is being used. Not only that, but the product must be packaged as to contain the product adequately to ensure that it does not become contaminated by the surroundings, to provide vital information about product identity, handling information and any potential hazards to shippers and users. Due to environmental concerns packaging practises have undergone scrutiny by governments, regulatory agencies, consumer groups and environmentalists. It is becoming increasingly important that packaging is produced in a reasonable manner, is recycled when economically feasible and permitted by regulation, and is used in an efficient manner so as to ensure no wastage occurs where possible and to minimise usage of materials. Most products can be stored and transported by most means of packaging; the choice of the type of packaging is taken usually by the manufacturer for economic or marketing reasons. For a chemical however the choice of packaging is mainly dictated by safety priorities and chemical compatibility factors. In this case, for physical distribution the cost of the packaging can be comparable to the manufacturing costs of the product and this in turn will have a knock-on effect for the cost of the product for the consumer. Regulations regarding how a chemical product is packaged and shipped depend on whether the chemical is classified as hazardous or nonhazardous. Nonhazardous chemical substances are shipped and packaged subject to the rules of the carrier. The most common rules are those published in National Motor Freight Classification for trucks and Uniform Freight Classification for railroads. If items are not packaged according to the classification requirements then the carriers have a right to collect a surcharge and refuse paying handling or damage claims on such items. The regulations controlling packaging for hazardous materials are different. The primary document The Hazardous Materials Regulations (HMR) devised in the Code of Federal Regulations was changed in order to bring it to par with international rules and to enhance safety through better classification and packaging. The primary change was to replace specific containers with performance oriented packaging. This means that as long a s a packaging system passes test requirements it can be used. Certification of a package is now the responsibility of the shipper. Tests on packaging must be approved by a test laboratory and in turn this laboratory must be approved by the Department of Transport (DOT). Hazardous materials are regulated according to how they are classified. The HMR provides a table classifying the types of hazardous materials. There are 9 classes some with subdivisions. HMR Classification Class Subdivision Explosives 1.1 Mass Explosion Hazard 1.2 Projection Hazard; no mass explosion hazard 1.3 Fire hazard and minor projection or blast 1.4 No significant blast hazard 1.5 Very insensitive mass explosion hazard 1.6 Extremely insensitive detonating substances Compressed Gases 2.1 Flammable Gas 2.2 Non-flammable Gas 2.3 Poison Gas Flammable Liquids Flammable Solids 4.1 Flammable Solid 4.2 Spontaneously Combustible 4.3 Dangerous When Wet Oxidising Substances and Organic Peroxides 5.1 Oxidizer 5.2 Organic Peroxide Poisonous and infectious Substances 6.1 Poisonous Substances 6.2 Infectious Substances Radioactive Materials Corrosives Miscellaneous dangerous Substances Fig 3. Kirk Othmer (1991-1998) Packaging requirements for hazardous materials are determined by finding them listed in Hazardous Materials table of 49 CFR, section 172. From this the hazard class, packaging group, identification number, label requirements, packaging authorisations and special provisions can be ascertained from this. All types of designed packaging must be tested before approval. If approved, it must be marked with the UN packaging marking which specify any details pertaining to the packaged material such as the type of material, relative density of the material and maximum gross weight for which the packaging has been tested, the packaging group for which the package has been approved, whether the material is solid or under pressure, the state or country of origin, the year of manufacture and the testing facility. When the package is ready for shipment it must be labelled with the identification number and shipping name in the top left corner, the hazardous materials label in the centre of the pan el, and the package marking in the bottom left corner. Shipping documents must also show the hazardous materials identification, the hazard class and an emergency telephone number. Improper packaging procedures including improper shipping documents, marking or handling can result in civil and/or criminal liabilities against the carrier, shipper or the packaging manufacturer. Hazardous Pollutants The chemical process industry is one of the most highly regulated industries in the world. It is regulated regarding areas of environmental protection, health and safety. Everything is affected by the chemical industry, the siting of a new location for a facility, the transportation of raw materials and finished products, working conditions for employees, packaging of finished materials and interactions with the community. The chemical industry also develops additional regulations alongside the regulatory agencies to ensure the proper protection of the community, the environment and the employees. For example, The Chemical Manufacturers Association (CMA) brought out the Responsible Care Initiative. This initiative, initially started in Canada, is a commitment on behalf of the chemical industry to continuously improve health, safety and environmental standards and to respond to public concerns. The initiative is implemented by 6 codes of management practices which cover Community Awar eness and Emergency Response (CAER), Employee Health and Safety, Distribution, Process Safety, Pollution Prevention and Product Stewardship. More than 35 countries in the world have taken on responsible care and are developing their own means of implementation. Uniformity to environmental standards was attempted by the International Standard Organisation (ISO) by following up the ISO 9000 series of quality standards with the ISO 14000 environmental management standards. For example ISO 14001, Environmental Management Systems, is a statement of environmental policy which includes the commitment to comply with environmental legislation and a commitment to ensure continual improvement; it also ensures that environmental objectives within the plant are identified, management representatives that ensure that the companies plans are implemented and procedures that might detect any noncompliance to such standards by means of periodic environmental management system audits are carried out. Any company wishing to do business in the international market will need ISO 14001 certification. Environmental Protection Water For a long time in the US water pollution control were taken on a basis of water quality standards for bodies of water such as streams, lakes and rivers, receiving bodies of water. There was no effective, national legal authority which limited the discharge of pollutants into bodies of water and was regulated more so on a state-by-state basis. In the late 1960s the US revived the 1899 Refuse Act which prohibited discharging anything into navigable water unless certain permits were obtained. This provided a new control over discharges of materials by industry. Along with this, legislation from the Federal Water Pollution Control Act Amendments (FWPCA) was put forward with an objective to restore and maintain the chemical, physical, and biological integrity of the nations waters. Kirk Othmer (1991-1998). New water quality standards were introduced by means of stream use classification. This gave control to states to decide what they would use their water for. The EPA defined 4 categori es. Class A Primary water contact recreation Class B Propagation of desirable aquatic life Class C Public water supplies prior to treatment and Class D Agricultural and industrial uses After this, water quality criteria were to be developed. This means that for each designated water use there were going to be limits to the allowed concentration of pollutants. Limits of discharged effluent were controlled by means of regulating the unit weight of pollutant discharged per mass of product manufactured, rather than measuring the overall concentration of pollutant in a discharge stream. In this way chemical industries would be unable to dilute chemical pollutants to avoid surpassing concentration limits. Air 2500 years ago lead pollution produced by silver smelters in Rome and Greece were a major cause of concern. Analysis of lake sediments has shown that this lead pollution has spread across the northern hemisphere. Air pollution caused in the modern working environment is usually due to burning of fossil fuels and as early as the 13th century this has been attributed to the burning of coal. The main cause for concern with coal burning was the unpleasant sulfurous odour released and the soot produced but the health effects caused by this has not been made clear until recently. National Ambient Air Quality Standards 6 pollutants that cause major concern have been classed by the EPA under The Clean Air Act 1970. These are Sulfur Oxides (SOx), nitrogen oxides (NOx), lead, particulates i.e. (subdivisions of solid or liquid matter suspended in a gas), and photochemical oxidants (ozone).The EPA developed National Ambient Air Quality Standards (NAAQS) to combat levels of air pollution based on the level of highest concentration that would have no adverse effects on the environment or on human health. These standards are expressed by ground level concentrations where the concentrations of pollutants are measured at ground level in measurements of parts per million or micrograms per cubic metre. Solid and hazardous waste Implementation of laws concerning the control of pollution due to solid waste disposal was formulated much slower than for those were for water and air. The Resource Conservation and Recovery Act 1976 (RCRA) was the first act passed where newer substantial controls were authorised. The objective of the RCRA was to conserve public health, the environment and natural resources. It was implemented to ensure that practices regarding the production, storage, transportation and disposal of waste would minimise or completely eradicate the hazard to human health and the environment. The section of the RCRA that caused the most concern to the Chemical Industry was subtitle C. This was the hazardous waste management regulations. The objective of this was to monitor and regulate hazardous waste from the time of production to its disposal. Facilities which would work in the transportation, storage, treatment or generation of hazardous waste are covered by these regulations. The definition of a s olid waste to the RCRA covers a broad category of substances including solids, semisolids or liquids or any contained gaseous materials. A hazardous waste is a substance that must be either listed by the EPA or have a hazardous characteristic Kirk Othmer (1991-1998). Certain types of solid wastes are excluded from the hazardous materials regulations specifically for the large volume by which they are produced or other reasons. These would include household wastes, fossil fuel combustion, exploration wastes and some agricultural and mining wastes. A solid waste is considered hazardous if it is listed in the EPA or has a specific characteristic hazard. There are four characteristics of hazardous wastes: reactivity, corrosivity, ignitability and toxicity. Toxicity refers to how leachable the waste is and the toxicity in the groundwater that would result using Toxicity Characteristic Leaching Procedure, an analytical method. Some examples of hazards included in TCLP are listed in the ta ble below. Maximum Concentration of Contaminants for Toxicity Characteristic Contaminant Regulatory Level (mg/L) Arsenic 5.0 Benzene 0.5 Silver 5.0 Lead 5.0 Mercury 0.2 Chloroform 6.0 Chromium 5.0 Selenium 1.0 Fig 4. Kirk Othmer (1991-1998) It is the responsibility of the producer of the substance to determine whether it is hazardous. They are required to hold records; label substances correctly, inform transporters and report to the EPA periodically. Groundwater and air quality are monitored for any facility that could potentially produce emissions. Any regulations concerning nonhazardous waste are controlled by the local and state authorities. Due to increased pressure on landfill sites these regulations are getting more stringent for nonhazardous solid waste. Better management of nonhazardous waste is encouraged through recycling, reduction and reuse. Industrial Hygiene Industrial hygiene is a profession devoted to anticipating, evaluating and recognising any environmental factors or stresses arising in the workplace which could cause impaired health and wellbeing, sickness, inefficiency and significant discomfort between workers and those of the local community. In the U.S., industrial hygienists are usually members of the American Industrial Hygiene Association (AIHA) or other groups such as the American Academy of Industrial Hygiene (AAIH). Industrial Hygienists work with other professions concerning health in the workplace such as safety engineers and occupational health nursing. All these groups work in implementing the laws regarding the regulation of health and safety in the workplace. The principal laws are the Occupational Safety and Health Act (OSHA) in the U.S. but similar laws are put into place all over the world which are proposed by International Organisations such as the International Labour Organisation (ILO) and the World Health Or ganisation (WHO). Hazards arising from the workplace which industrial hygienists are interested in would include the following categories. Chemical Carcinogens, Reproductive Hazards, Acute Poisons, Irritants, Corrosives, Neurotoxins Ergonomic Repetitive Strain Injury (RSI), Back injury, Carpal Tunnel Syndrome, Human-Machine interaction Physical Noise, Cold, Heat, Ionising Radiation, Extremely Low Frequency Radiation (ELF), Ultraviolet Radiation, Laser Radiation, Infra Red Radiation Industrial Hygienists must be able to detect what potential hazards might result from workplace materials, to evaluate hazards and determine how much risk is posed by it, and to recognise hazards as they occur. The best and cheapest way to approach workplace hazards is to anticipate them and if possible to completely prevent them from happening. When a new chemical process is conceived an industrial hygienist must check the toxicology of the substance produced, either by animal testing or by human epidemiology. Some substances are self limiting, others are potent and carcinogenic but most chemicals lie somewhere in between. Wherever possible it is encouraged to abstain from using potentially dangerous chemicals. Also potentially damaging physical hazards which arise from certain processes such as excessive heat, noise or pressures must also be anticipated and avoided where possible. Usually industrial hygienists are capable in devising methods of using hazardous chemical substances safely. To recognise potential hazards industrial hygienists must have an extensive knowledge of the kind of hazards that may occur in types of industry. Recognising hazards is done by looking for sources of harmful chemical or physical agents that would cause damage if exposed to workers. Fugitive emissions are an example of an industrial hazard, and occur when there is a break in the barrier which provides containment for the chemical process. The main source of loss can be attributed to seal and flange leaks where material could escape. Even though the emissions can be incredibly small so that they are undetectable by a material balance, they can however build up in the work area which could lead to overexposure to harmful chemicals. Valve stem leaks are one example. These can worsen over time if not corrected. Pump seal leaks which are usually quite small can become large if there is total seal fail

Mobile Location Techniques

Mobile Location Techniques INTRODUCTION: With the rapid increase in number of mobile users, a massive number of calls originate from mobile subscribers, all over the world, everyday. With the increasing number of mobile users and originating calls, there is also an increase in emergency calls that originate from mobile stations. In many emergency cases the position is unknown to the caller, or he cannot explain properly. Thus there is a strong need to locate any mobile user in emergency situation. Hence the scope of mobile positioning is vital. Due to importance of mobile positioning, the need to locate any mobile user in emergency was also called by Federal Communications Commission (FCC) and European Countries. For instance, the Federal Communications Commission (FCC) made a proposal to include location in the 911 emergency service number, which resulted in the E911 ruling [2]. Currently, all the legacy handsets used in public cellular networks in the USA must provide the location of the customer whenever this number is dialled. The European Commission (EC) adopted a similar regulation to include location in emergency services on 112 [2]. The FCC in USA took the first step in this direction. Initially by 2001, the mobile operators are required to provide the accurate location of an emergency caller. The current requirement of FCC is to locate 67% of emergency callers must be located within 100 meters and 95% of the callers must be located with an error of no more than 300 meters. [3] Applications: Mobile location can be used for a number of services by mobile operators. Some of them are discussed here: An important application of mobile location is to provide emergency services. By knowing the location of a mobile user, emergency vehicle can be directed to that location. Hence there is an increase in public safety and services. Another interest in exploiting the mobile location is to apply location sensitive billing. By knowing the location of mobile subscribers an operator can offer competitive tariff e.g. users can be offered more calls from their mobile to home or office. Asset tracking and fleet management is another application of mobile location. Using the location of mobile travellers can be informed about location. Mobile location can be used to effectively manage fleet and traffic conditions. There are two main categories for mobile positioning,Handset Based positioning and Network based positioning. Handset Based techniques needs special type of handset hardware or the installation of specialized network software in existing handsets e.g. GPS and A-GPS. GPS receiver determines its own position by sending and receiving signals from at least four satellites. The time to reach satellite signal to GPS receiver is used as a parameter. The accuracy of GPS based systems is very high. And the coverage of satellite is very good in outdoor environment. However, drawback is inability of GPS to operate in indoor and heavily populated urban environment. GPS lacks positioning where signals of the satellite cannot be fully covered. Another problem is related to existing handsets in market. A large number of existing handsets lack the built in GPS receivers. Thus using this method a huge number of people can not get benefit or can not be located in case of emergency. Also Embedding a GP S receiver into mobile devices leads to increased cost, size, and battery consumption [1]. Thus hundreds of millions of handsets in market need to be replaced or modified. In contrast, Network Based Techniques determine the position of a mobile user by measuring its signal parameters when received at the network Base Station (BS). Here BS receives signal from Mobile Station (MS) and sends them to a central site where location estimation algorithms are used to estimate location. In this method there is no need to change or replace existing handsets. It would require change in a few thousands of network nodes (Base Stations) than to change hundred of thousands of mobile stations. Hence, it can be implemented easily, less costly using existing technology. And still can provide a very good estimate of position of a mobile user. The future technologies also support network based positioning. Infact many positioning techniques can not be implemented using existing GSM technology. Using advanced technologies their efficiency will greatly increase. The Network based positioning is also feasible for network operators as it would help them to implement location sensitive billing and location related services. Thus based on a certain location the operator can implement a specific price plan e.g. less price calls to home or office number. It will also help them to generate more revenue. Another advantage of network based techniques is the security of the subscribers. Using an algorithm at network side also ensures that the position of subscriber is known only to emergency service or mobile operator. Thus it also increases the safety and security of the subscribers. The network based techniques have several advantages like low cost, ease of implementation, implementation using existing technologies and methods, beneficial for a large number of people. However, the main issue with this technique is its accuracy. Despite a number of efforts to reduce error and increase accuracy there is still no unbiased estimation method present. All of the methods produce good results under certain conditions or circumstances. Thus there is no general prediction for result using an algorithm. The main problems in incorrect positioning are multipath propagation, fading and low SNR. The efforts are continuously being made to minimize these and hence increase accuracy and thus performance. The project will emphasize on comparing various existing network based location techniques. Some of the common techniques will be studied in detail. Base on these existing methods, a number of positioning algorithms are also studied in detail to implement major positioning techniques. The algorithms will then be implemented using MATLAB. The results of algorithms will be compared to actual position of mobile station so as to measure the performance of each of them. Final thing is to develop an online benchmarking tool to compare location evaluation estimates using different techniques. The tool should be able to run user uploaded measurements in to its own algorithms. The results will then be compared to user submitted results to perform a benchmark. Existing Literature Review A number of mobile location techniques are common nowadays. These techniques can be divided into three main types: Mobile Based Techniques Network Based Techniques Indirect Techniques These techniques are briefly explained below: Mobile Based Techniques: In this method, a number of geographically separated transmitters are used by the mobile station to exploit its own position. It is also known as Self Positioning. Thus mobile station (MS) locates itself by using signals from a number of transmitters or base stations (BS). Example of mobile based positioning is GPS and A-GPS. In GPS based positioning GPS receiver uses signals from geographically distributed satellites to exploit its own position. Network Based Techniques: This method uses a number of transmitters in a network to locate position of an unknown receiver. It uses resources of the network only. The signals from the MS are used by a number of BS to locate the MS. This technique can be implemented using different type of parameters e.g. Cell Global Identity (CGI), Cell Global Identity with Timing Advance (CGI-TA), Enhanced Cell Global Identity (E-CGI), Time of Arrival (TOA), Angle of Arrival (AOA), Time Difference of Arrival (TDOA). Indirect Techniques: In this technique mobile or network can be assisted to locate a mobile station. Thus base station can send positioning data to mobile station to locate itself. Similarly measurements can be uploaded from MS to BS to locate mobile station. It involves measurements sent from MS to BS for positioning at BS or vice versa. There are a number of network based mobile positioning techniques in use today. In such techniques a number of involved base stations (BS) use signal from mobile station (MS) to locate the position of MS. The common methods are Signal Strength, Time of Arrival, Time Difference of Arrival, Angle of Arrival, or hybrid techniques. Each of the existing method has its own advantages and disadvantages. A major problem with all methods is the accuracy. It depends on cell size, cell environment, number of cells, multipath propagations and distance between MS and serving base station. Some other common parameters for performance measurement include applicability, robustness, etc. The existing methods have been described in detail below: Cell Global Identity: The CGI method to locate a mobile user is most easy and straight forward. In this method, the position of mobile user is estimated by using the cell identity of serving base station. Thus the mobile can be located anywhere in a call coverage area. It is very simple to implement. However, the positioning error may range from a few meters to a few kilometres. The accuracy will be dependent on the size of serving base station. Another problem with this method is that mobile station is not always connected to nearest base station. In this case the location of mobile cannot be even estimated. Enhanced-CGI: To overcome errors in basic CGI technique another method is used. The basic idea was to split the coverage area of a base station into two or more areas, mostly three 120 degree areas. Each area within a base station can then be issued with a separate identity. Hence in this way the position of mobile can be narrow down to a small area. Although this method is easy to implement yet error is large enough from practical point of view. CGI with Timing Advance: The CGI technique can also be improved by using the timing advance feature of GSM. Timing advance is a value that corresponds to the time it takes for a signal to reach from MS to BS. In GSM timing advance is a feature used by the base station to synchronise with mobile station. On step timing advance is equal to a change in 1100 m of round-trip time (the time signal takes to reach from base station to mobile and then back to base station). The timing advance is assigned by base station for each mobile station. Using the timing advance feature a mobile user can be located within 550 meters approximately. Time of Arrival: Although CGI method provides a good estimation of mobile position, the error is still large enough from emergency view point. Another method to locate mobile is using the arrival time of signals at base stations involved. The distance of mobile can be estimated by using information about time of arrival i.e. D = t / c Where t is the time of arrival of signal at base station and c is the speed of light. The distance will be the estimated mobile position. However the mobile can be located anywhere on circular path centred at base station and radius equal to estimated distance D. The exact position of mobile can be estimated by using same type of measurements from two other neighbouring base stations. Ideally the positioning circles from all the three base stations must intersect at a point, which will be the position of mobile. However, practically, the circles dont intersect at a single point rather they make a small area in which the mobile is potentially located. This method is really better than CGI because it gives more accurate results. The time of arrival method requires accurate synchronization or reference between mobile and base station to correctly measure the arrival time. The results, however, depends on environment of cell clutter, atmospheric conditions, and multipath propagation. In worst atmospheric conditions the results may vary severely. Angle of Arrival: In this method the position of the mobile is located by using the direction of signal arriving from mobile station to the serving and, at least one other base station. The direction or angle of arrival is measured at base station by using arrays of antennas. Angle measurement at one base station will give the position of mobile to be located at a straight line at a certain angle with base station. Measurement from another involved base station will produce another positioning line. Ideally the mobile must be located at the intersection of two lines from involved base stations. In practice, however, they may not intersect at all at a single point. The angle of arrival is good because it can be implemented using a small number of base stations. Thus it is best when the number of base stations visible to mobile is very low. The angle of arrival method is very sensitive to measurement errors of angle. So a very small error in angle measurement results in a much larger error in position o f mobile. Time Difference of Arrival: The time of arrival method requires a strict synchronisation or reference between mobile and base station. To overcome this problem, the difference of arrival time at a pair of base station is used for measurements. A pair of base stations is used to record one time difference measurement. The result will be a circle on which mobile can be anywhere. Ideally the three circles will intersect at one point. This point will be the position of mobile. In actual practice the method will give a small area in which mobile must be located. The difference of arrival time eliminates the need of synchronisation as required by time of arrival. This method can be used as to run entirely on network side or to run with mobile assistance. The performance of time difference method is greatly improved than time of arrival. The main advantage of this method is elimination of timing requirement. However, on the other hand, the number of involved base station must be at least four including primary base st ation. Thus only then three sets of measurements can be obtained. The time difference of arrival method is more frequently used due to ease of implementation. Data correlation method: The Database Correlation Method makes use of the signal information seen by mobile station. The signal information from all of the coverage area seen by mobile station is stored in a database at network side. The signal information may include signal strength, signal timing, signal delay etc. When position of the mobile is required, the stored data in database is used by a positioning server to do so. The signal measurements sent to the database depends on the environment. The resolution of such measurements must be set so as to achieve certain accuracy. In GSM a sub-band resolution is used by the Base Station Controller (BSC) to facilitate the handover process. Pilot Correlation Method: Algorithms Search: There are a number of positioning algorithms in present literature. These algorithms make use of the measurements done by the mobile station. The measurements required for each algorithm may vary. However, some common measurements may include Cell ID, LAC, Signal Strength, Timing Advance, Time of Arrival, and Direction (Angle) of Arrival. Also these measurements may be carried out only on network side i.e., by primary base station or they can be performed with assistance of mobile station. The algorithms for all of the major positioning methods are studied in detail. Although there is a large number of algorithms in literature yet each of them has own advantages and disadvantages. Each algorithm is based on some assumptions and limitations. For this reason we can not say which one is best. But the one which gives acceptable accuracy is thought to be the good one. Cell Global Identity (CGI): The Cell ID is the very basic method to locate mobile station. It is used to make a rough estimate of mobile position. With this method the mobile can be located anywhere within a cell. Thus the accuracy is very poor. The mobile station measures periodically the id of serving base station and up to 6 neighbouring base station. Thus no special algorithm is needed to locate Cell ID. By looking at mobile measurements the Cell ID can be located. Enhanced Cell ID: Due to very poor accuracy of basic Cell ID, a number of enhancements have been made to it. Thus measurements like signal strength, Timing Advance can be used in conjunction with Cell ID to improve accuracy. Two algorithms which show good results are Enhancement to CGI using Signal Strength and Positioning using Timing Advance. In the first algorithm the signal strength is taken as a parameter. The power received by mobile station from primary base station and up to six neighbouring cells is feedback to primary base station. The primary base station thus knows the power transmitted by it and power received by mobile station. Then the distance calculation is possible by using the known path loss. Using Okumura-Hata Path Loss model [4] the distance between mobile and base station is calculated. The mathematical form of this model is [4]; Urban areas: LdB = A + B log10 R E Suburban areas: LdB = A + B log10 R C Open areas: LdB = A + B log10 R D A = 69.55 + 26.16 log10 fc 13.82 log10 hb B = 44.9 6.55 log10 hb C = 2 (log10 (fc / 28))2 + 5.4 D = 4.78 ( log10 fc )2 + 18.33 log10 fc + 40.94 E = 3.2 ( log10 ( 11.7554 hm ))2 4.97 for large cities, fc = 300MHz E = 8.29 ( log10 ( 1.54 hm ))2 1.1 for large cities, fc E = ( 1.1 log10 fc 0.7 ) hm ( 1.56 log10 fc 0.8 ) for medium to small cities Definition of parameters: hm mobile station antenna height above local terrain height [m] dm distance between the mobile and the building h0 typically height of a building above local terrain height [m] lhbbase station antenna height above local terrain height [m] rgreat circle distance between base station and mobile [m] R=r x 10-3 great circle distance between base station and mobile [km] f carrier frequency [Hz] fc=f x 10-6 carrier frequency [MHz] ? free space wavelength [m] This model is fairly simple so it is used for a large number of situations. The distance calculation is easy from this model using known path loss in pre-defined environment. The mobile will be located anywhere on the circle of estimated distance with centre at base station. A minimum of three base stations are used for such measurements. Ideally the three circles will intersect at a single point. This point will be the position of mobile station. The triangulation technique is used to find the intersection coordinates of circles. Time of Arrival: Although CGI provides the position of mobile station yet the accuracy is not sufficient for many purposes. To improve accuracy the time of arrival method is used. It gives good results than CGI in most of the situations. A number of algorithms describing time of arrival method are in literature. Each of them has some advantages and some short comings. Also each algorithm works best under some specific conditions e.g. in line of sight (LOS) or non-line of sight (NLOS) conditions. A good algorithm which gives acceptable results in many situations is A Constrained Least Squares Approach to Mobile Positioning: Algorithms and Optimality. This algorithm uses a least square approach to estimate position of mobile station. The distance between mobile station and base station is estimated by using the fact that signals travel in free space at a speed equal to speed of light. Thus mathematically, Di =Ti / c i = 1, 2 N Where D is the estimated distance, T is the TOA measurement, i denote the number of base station and c is the speed of light. The mobile station will be located anywhere on the circle with radius D centered at base station i. Same TOA measurements are performed by at least three base stations. The position of mobile will be the intersection of three circles. Ideally this will be a single point. But in practice, due to multipath propagation and fading, it will give a small area. The mobile station will be located in this area. To reduce positioning error the algorithm uses a least square error approach. Thus the distance between every point in that area and each mobile station is calculated. The point where the sum of squares of distances is minimized will be the estimated position of mobile station. To get TOA measurements, base station and mobile station must be synchronized properly or there must be a reference point. Thus a strict timing requirement is necessary. Angle of Arrival: In LOS conditions this method is the best to use. A number of algorithms describing this method are in literature. All of these algorithms require a dominant LOS path to correctly perform angle of arrival measurements at base station. Thus this method is best in open areas and suburban areas. In dense urban environment this technique produces severe errors due to NLOS and multipath propagation. A number of algorithms are studied in detail. A good algorithm is A Constrained Least Squares Approach to Mobile Positioning: Algorithms and Optimality. It produces results with acceptable accuracy. According to this algorithm, to perform angle of arrival measurements, base station must be provided with multiple antenna arrays. A minimum of two base stations will be required to perform such measurements. The signal from mobile station will reach base station at a certain angle with horizontal axis. This angle can be measured by base station using antenna arrays. Mathematically, it is given by tan (fi) =(y yi / x xi) , i = 1, 2, . . . , M. The angle of arrival measurement from one base station will result in a straight line. This line is also called Line of Bearing (LOB). It will be at a certain angle between horizontal axis and base station. The mobile will be located any where on the LOB. A similar measurement will be done using another involved base station. It will result in producing another angle of arrival or LOB. The point where the two line of bearing intersects will be the position of mobile station. Ideally two lines will intersect at a unique point. However, practically they may not intersect at a point. In this situation the angle of arrival method need further measurements from other involved base station. This method produces very accurate results in LOS situation. However, the results depend critically on the measured angle. Thus a very small error in angle measurement may lead to positioning error of hundreds of meters. Another disadvantage is the cost of this method. It requires antenna arrays at each base station to measure AOA. Hence cost of implementation increases. Time Difference of Arrival: The time difference of arrival uses the difference in arrival times of signals at a pair of base stations. The time difference of arrival measurements are done with reference to primary base station. A good algorithm in literature is the Performance Comparison of TOA and TDOA Based Location Estimation Algorithms in LOS Environment. It explains the working of different types of TDOA approach. It also compares the performance of each of the type. However it uses a LOS approach. In open areas LOS assumption is valid but in heavily populated urban areas this assumption is invalid. Another good algorithm which explains the TDOA measurements is is A Constrained Least Squares Approach to Mobile Positioning: Algorithms and Optimality . In this algorithm, the primary (Serving) base station is the reference base station. The time of arrival measurements are performed using the reference base station. Thus the estimated distance between mobile station and reference base station is d1 and that of mobile station and a neighbouring base station is di. Thus the TDOA measurements are given by, d1 = t1 / c di = ti / c, i = 2,3 .. N Where d1 is the distance between mobile station and reference (primary) base station and di are the distances between mobile station and other three neighbouring base stations. The TDOA measurement between reference and second base station is given by TDOA= d1-di i = 2,3, .N This will be the error free TDOA measurement at a pair of base stations. The measurement including error is given by; TDOA= (d1 di) + error The error is modelled as a Gaussian distributed random variable with zero-mean. Such measurements are taken from at least three pairs of base stations. The triangulation technique is then employed to get the position of mobile station. The TDOA method is superior to time of arrival (TOA) in sense that it eliminates the need for timing reference. Thus it is easy to implement. Due to no timing requirement TDOA method is more frequently used than TOA method. Database correlation method: Despite of a number of algorithm which perform fairly well in urban areas there is still a need to further improve it. Due to severe multipath and fading effects LOS assumption is not valid in urban areas. The Database Correlation Method is a good method to counter effect multi path and fading. It can be implemented by utilizing the measurements performed in existing GSM systems. It can be implemented by making Signal Strength as a parameter. A ggod algorithm to implement Database Correlation Method is Database Correlation Method for GSM Location by Heikki Laitinen, Jaakko Lahteenmaki, Tero Nordstrom'. In this algorithm the DCM is implemented by using signal strength measurements performed by handset. The algorithm explains the way database correlation method can be implemented in GSM. The measurements performed in the coverage area are performed by mobile station and are stored in database. Thus the database will consists pre-measured samples of signal measurements in the coverage l ocation. When the need to locate mobile station arises, the primary base station asks mobile station to perform signal strength measurements and feedback to it. The BS sends these measurements to location server. The location server then calculates the difference between stored fingerprint and actual measurement. The point where the difference between fingerprint and actual measurement is minimum will be the estimated position of mobile station. The estimated position will also contain some error in it due to fading, NLOS path and multipath propagation. However this error will be drastically less than the error in other techniques applied under same conditions. The database correlation method has the advantage that it can be implemented in any type of system like GSM, CDMA,UMTS,etc. References: Network-Based Wireless Location IEEE SIGNAL PROCESSING MAGAZINE JULY 2005 A New Time-Based Algorithm for Positioning Mobile Terminals in Wireless NetworksIsrael Martin-Escalona and Francisco Barcelo-Arroyo, EURASIP Journal on Advances in Signal Processing Mobile Positioning Using Wireless NetworksIEEE SIGNAL PROCESSING MAGAZINE JULY 2005 Path loss models S-72.333 Physical layer methods in wireless communication systems Sylvain Ranvier / Radio Laboratory / TKK 23 November 2004 Performance Comparison of TOA and TDOA Based Location Estimation Algorithms in LOS Environment Guowei Shen, Rudolf Zetik, and Reiner S. Thoma A Constrained Least Squares Approach to Mobile Positioning: Algorithms and Optimality K.W. Cheung,1 H. C. So,1 W.-K.Ma,2 and Y. T. Chan3 Database Correlation Method for GSM Location Heikki Laitinen, Jaakko Lahteenmaki, Tero Nordstrom

Economics of Marriage :: essays research papers

Economics of Marriage Nowadays, marriage is hardly a new subject of discussion and is found in every human society. Any marriage involves two individuals each of whom has their own experience of that marriage. Nowadays, the roles and expectations that the families have to fulfill are distributed evenly among the members of the family. What this means is that mothers, who were identified in the past as household wives (since they were responsible with cleaning, cooking and raising children) are granted with more rights such as the right to participate in a voting process or the right to get a job. As oppose to mothers, fathers have always been mainly responsible with working hard to support their families because in most of the situations, they were the main financial providers. As a result, they had to bring money to their families by any means even if that meant getting more than one job. This situation became much more problematic when children appeared in the families. As we all know, children had and will always play an extremely important role and raising them is a big responsibility for thei r parents. Having children and only one member of the family (for instance the father) working is a familiar situation for most families. In this case, the father has to be more realistic than ever that his family relies on his financial support. He has to make sure that his family has the necessary supplies to survive. If this situation is not being resolved due to various reasons such as the husband does not earn enough money or just simply refuses to contribute financially, conflicts and issues may arise which often lead to family separations, and thus, poor living conditions and even death from malnutrition. This is exactly the situation that parents have to avoid. They have to be more responsible and realistic of their own actions, and take the decisions that are in the best interest of the family, the right decisions. These types of marriages are called emotional and financial support marriages. Another type of marriages that are very common nowadays and very numerous on a wide scale are the economic marriages. Economic marriages are essentially those kind of marriages in which money play a tremendous role in the lives of one or more couples. This is often a situation in which one or even both individuals involved in marriage have an unconditional desire and hunger for money.

Suffering in Charles Dickens Oliver Twist and James Watsons Talking in Whispers :: English Literature

Suffering in Charles Dickens' 'Oliver Twist' and James Watson's 'Talking in Whispers' I am going to explore the ways in which human suffering is portrayed in Charles Dickens' 'Oliver Twist' and James Watson's 'Talking in Whispers'. I am also going to explore the ways in which sympathy is created for the characters Oliver Twist and Andres Larreta. With consideration of Oliver Twist's and Andres Larreta's suffering I am going to see if they can be considered as heroes. I am going to do all of this by analysing areas of the novels, 'Oliver Twist' and 'Talking in Whispers'. Oliver Twist and Andres Larreta both experience a great deal of suffering. They experience physical, emotional and mental suffering. The societies in which they are a part of also suffer. The suffering of society in both novels 'Oliver Twist' and 'Talking in Whispers' are caused by the authorities. However, the society in 'Talking in Whispers' seems to be much bigger than the society that comes across in 'Oliver Twist'. I think this is because 'Oliver Twist' is mainly about the life of Oliver Twist and how he reunites with some of his relatives, whereas 'Talking in Whispers' mainly focuses on Andres Larreta's life and Chile under dictatorship. It also has lots of information about the Chileans as a whole. Both character's Andres Larreta and Oliver Twist possess heroic qualities. I believe they are both heroes for surviving the suffering they had received. Oliver Twist and Andres Larreta both experience physical and emotional suffering. Oliver Twist is a young child, below the age of 10 years. He experiences a great deal of physical suffering. Oliver experiences abuse at the workhouse. He was very poor and had little food, which made him hungry. He had to work to stay alive. Although his work only earned him just about enough to survive. "The hungry and destitute situation of the infant orphan was duly reported by the workhouse authorities." The author Charles Dickens states that Oliver is hungry and is in a poor situation. Another instance of physical suffering Oliver experiences, is the beating he receives after he has a fight with Noah. "Oliver's clothes had been torn in the beating he had received; his face was bruised and scratched; and his hair scattered over his forehead." Dickens describes his condition and implies to the reader that his beating was rough, violent and severe. He makes the reader sympathise with Oliver. Not only is this physical suffering for Oliver, but for a child as young as Oliver it is also emotional suffering. It leads him to believe nobody cares for him and that he is

Atticus As A Model Parent :: essays research papers

In To Kill a Mockingbird, Harper Lee suggests that Atticus is a model parent. Atticus gives guidance to Jem and Scout, and he treats them with fairness and honesty. He tries to bring them up as best he can as a single parent. Atticus is always guiding Jem and Scout with advice so that they will become more compassionate people. Atticus sets a good example for the children when Mr Ewell confronts him. Even though he is provoked and insulted, Atticus simply has a â€Å"peaceful reaction†. This shows the children never to get into fights with people when they are upset about something. Atticus shows children about courage and all the forms it appears in. When Jem is told to read for Ms Dubose and she dies, Atticus explains to Jem about her morphine addiction, and how she died â€Å"free†. This shows Jem that courage isn’t always where you expect to find it, and that if you have some compassion, you see people for who they really are. The most important piece of advice he gives his children is that â€Å"you never really understand a person until you consider things from his point of view†¦ until you climb into his skin and walk around in it.† This is important for the childre n to know, because it helps them to be more caring people, and they use this advice throughout the novel. Atticus treats everyone with fairness. He always hears both sides of the story. He does this after Scout has gotten into a fight with Francis Hancock. After a time Atticus hears Scout’s side of the story and realises that it wasn’t totally Scout’s fault. Scout also tells Uncle Jack that when she and Jem get into fights Atticus stops to hear both sides of the argument before placing the blame, if any. When he is confronted by awkward issues Atticus never tries to hide or cover up the truth. He tells Uncle Jack at Finches landing that when a child asks you something, â€Å"answer him, for goodness sake.† After Atticus is confronted by the mob outside the county jail, he doesn’t try to pretend that they weren’t there to hurt him. He admits that Mr Cunningham might have â€Å"hurt me a little.† When Scout asks Atticus if they are poor, the usual response would be to say no, so as not to scare Scout.

Elephant

Elephant was a movie based on an average high school In the last ten years, showing the experiences, different emotions and actions students have. While this movie In the end focuses on two boys, we see many different students throughout the movie and their part In high school. Even though this Is to be based on an average high school, I believe at times they showed an unrealistic portrayal on students and teachers with some of their actions in this movie.Not far into the movie they show a cone of girls in gym class, all wearing shorts outside except one, Michelle. Which is nothing wrong with that, but what happens is the teachers makes a comment on her wearing sweats, telling her she needs to Join the rest of the girls, by wearing shorts. Otherwise, by her not following these instructions, it would lead to a drop in her marks. Michelle to me seems like an insecure girl, not wanting to show her body off.And no school I feel would make girls who are insecure about their body have to f eel uncomfortable by wearing shorts, Just because every other girl in class was confident and wears shorts. I also found this movie made students look stupid, making them so oblivious to what was happening around them. As the two boys enter the school, stalking around the halls with those massive guns In their hands, you see not one student scream or even notice what was happening.Especially in the library which was full of kids, one of the boys marched right in, gun in the air, and it takes for him o actually shoot it after awhile for anyone to scream or run. Not to mention how as the shooting starts, students weren't even running out of the school. In so many of the scenes when you see students running away they completely ignore the doors as if they weren't even there. They Just run past or go up the stairs. No student would actually choose to run up a couple flights of stairs then to just run outside, getting away from this tragedy.

Women in Heart of Darkness by Joseph Conrad

Name: Date: French van Errors 9 March 2014 Archimedes Teacher Training Institute, university of Utrecht Course: Institute: Highlights of English Literature Essay on the role of women in Heart of Darkness by J. Conrad Assignment: Lovers In a Male-Dominated World: the Witch and the Widow ‘The last word he pronounced – was your name. ‘ It is ironic that this utter lie to a woman concludes the story of a man's Journey into the dark African jungle. Marrow, the story protagonist, is the one who lies to the fiance ©e of the infamous Mr.. Kurt, he reason for his African adventure.In Joseph Concord's novella Heart of Darkness (1899), women are scarce. Men drive the story and the two women portrayed In the story are sketchy, nameless characters who only serve as female prototypes: the Witch and the Widow. Both have been lovers of the story's pivotal Mr.. Kurt and symbolize his transformation. The first woman that appears is the Witch – traditionally an unmarried wom an outside the normal structure of society, a priestly woman who possesses unique knowledge of medicine and the supernatural. She comes on stage when the story Is well underway. Until then, only men have played a role In the tale: sailors, company officials, soldiers, station managers, explorers, servants and other staff. The Witch belongs to the tribe where Mr.. Kurt ruthlessly ruled. When he is taken away on Marrows steamer, she stands at the river bank: Along the lighted shore moved a wild and gorgeous apparition of a woman. (†¦ ) bizarre things, charms, gifts of witch-men, that hung about her, glittered and trembled at every step. She was savage and superb, wild-eyed and magnificent. Her long shadow fell to the water's edge.Her face had a tragic and fleece aspect of wild sorrow and of dumb pain. ‘ (up. 75-76 Penguin Classics) These words suggest she was Kurt' lover, but nothing beyond her awe-inspiring presence is revealed. Apart from the powerful African Witch, there is the brittle European Widow: two opposites that symbolize the former Kurt (nurtured by European civilization) and the new Kurt (transformed by African Nature). This black-clad woman also had an amorous relationship with Kurt, but she is completely unaware of Quartz's ramification and new love.She was engaged to him, waiting for his return and hoping to get married to him one day. Little did she know of his intentions to stay in the Jungle forever, had Marrow not got him out. She is presented as the prototypical widow that only exists because of her loss: ‘She came forward, all in black, with a pale since his death, more than a year since the news came; she seemed as though she would remember and mourn forever. ‘ (p. 92) We can conclude that males reign supreme in Concord's novella.They rule the world and they conquer the dark interior of the African continent. The primps inter pares of these conquerors is Mr.. Kurt, who nearly gets a mythical status in Marrows imagina tion. The two women that love Mr.. Kurt are the only women that play a role, and they are presented as symbols: the one a strong African Witch, the other a weak European Widow, enforcing the two-sided personality of Mr.. Kurt and his personal battle between the dark powers of Africa against the ‘enlightening civilization of Europe.